I did have an idea for arcade mode, and Time Trials. Instead of having the Circuit Experience in GTS, the AMG Academy in GT5, nor the various Senna events in GT6, the Time Trial mode as a whole could combine those three while also bringing back the time trial challenges seen in GT3, wherein each course layout could have a record set by a famous driver (either in the FIAGTCs, PD staff, or otherwise) in a given car, and you have to beat that record using the same car. The settings, obviously, would be disabled. Perhaps it could be more of a "Time Trial Challenge" sub-mode? (Alternatively, the mode we know as "time trial" was named "Free Run" in GT3, while the challenges were the ones collectively called "Time Trial," so maybe that naming could return.) But anyway, you could have challenges such as the following:
-All three Senna challenges from GT6, respectively for the 80s versions of Monza, Silverstone, and Brands Hatch Indy.
-Depending on which tracks & cars return, some of the original challenges from GT3 (set by PD staff) could also return, at least in spirit. So for example, at Laguna Seca, you could be tasked with using the Dodge Viper SRT10 Coupe instead of the GTS-R Concept.
-Other famous records and pole-setting times, such as the GT-R (R35) '07 record from GT5.
So you could have "Free Run" where you can pick any car and any track, and use that to set times, effectively being your Time Trial mode. (You would, of course, obtain a trophy for getting gold on all of these time trials.) But I also wonder what people thought of GT3's Single Race mode, wherein there was a progression of its own? I'm not too sure - on one hand, it does seem to add some legs to arcade mode, which is more than I can say for the Single Races in GTS where you don't really get anything for clearing races on harder difficulties. But on the other hand, it seems like more work than it'd be worth, for both the developer and player sides of things, and that online play and customization of the modes within it may be better.
I also wonder how Quick Match from GT6 could return? I.e. what could Quick Match do that Daily Races wouldn't be able to do? Perhaps Quick Match races could provide a different set of races for unranked play, to contrast with the ranked play in the Daily Races?